package org.apache.solr.highlight;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.lucene.search.Query;
import org.apache.solr.common.params.HighlightParams;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.core.SolrConfig;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.DocList;
import org.apache.solr.util.SolrPluginUtils;

public abstract class SolrHighlighter {
	public static Logger log = LoggerFactory.getLogger(SolrHighlighter.class);

	// Thread safe registry
	protected final Map<String, SolrFormatter> formatters = new HashMap<String, SolrFormatter>();

	// Thread safe registry
	protected final Map<String, SolrEncoder> encoders = new HashMap<String, SolrEncoder>();

	// Thread safe registry
	protected final Map<String, SolrFragmenter> fragmenters = new HashMap<String, SolrFragmenter>();

	// Thread safe registry
	protected final Map<String, SolrFragListBuilder> fragListBuilders = new HashMap<String, SolrFragListBuilder>();

	// Thread safe registry
	protected final Map<String, SolrFragmentsBuilder> fragmentsBuilders = new HashMap<String, SolrFragmentsBuilder>();

	// Thread safe registry
	protected final Map<String, SolrBoundaryScanner> boundaryScanners = new HashMap<String, SolrBoundaryScanner>();

	@Deprecated
	public abstract void initalize(SolrConfig config);

	/**
	 * Check whether Highlighting is enabled for this request.
	 * 
	 * @param params
	 *            The params controlling Highlighting
	 * @return <code>true</code> if highlighting enabled, <code>false</code> if
	 *         not.
	 */
	public boolean isHighlightingEnabled(SolrParams params) {
		return params.getBool(HighlightParams.HIGHLIGHT, false);
	}

	/**
	 * Return a String array of the fields to be highlighted. Falls back to the
	 * programatic defaults, or the default search field if the list of fields
	 * is not specified in either the handler configuration or the request.
	 * 
	 * @param query
	 *            The current Query
	 * @param request
	 *            The current SolrQueryRequest
	 * @param defaultFields
	 *            Programmatic default highlight fields, used if nothing is
	 *            specified in the handler config or the request.
	 */
	public String[] getHighlightFields(Query query, SolrQueryRequest request,
			String[] defaultFields) {
		String fields[] = request.getParams().getParams(HighlightParams.FIELDS);

		// if no fields specified in the request, or the handler, fall back to
		// programmatic default, or default search field.
		if (emptyArray(fields)) {
			// use default search field if highlight fieldlist not specified.
			if (emptyArray(defaultFields)) {
				String defaultSearchField = request.getSchema()
						.getDefaultSearchFieldName();
				fields = null == defaultSearchField ? new String[] {}
						: new String[] { defaultSearchField };
			} else {
				fields = defaultFields;
			}
		} else if (fields.length == 1) {
			if (fields[0].contains("*")) {
				// create a Java regular expression from the wildcard string
				String fieldRegex = fields[0].replaceAll("\\*", ".*");
				Collection<String> storedHighlightFieldNames = request
						.getSearcher().getStoredHighlightFieldNames();
				List<String> storedFieldsToHighlight = new ArrayList<String>();
				for (String storedFieldName : storedHighlightFieldNames) {
					if (storedFieldName.matches(fieldRegex)) {
						storedFieldsToHighlight.add(storedFieldName);
					}
				}
				fields = storedFieldsToHighlight.toArray(new String[] {});
			} else {
				// if there's a single request/handler value, it may be a
				// space/comma separated list
				fields = SolrPluginUtils.split(fields[0]);
			}
		}

		return fields;
	}

	protected boolean emptyArray(String[] arr) {
		return (arr == null || arr.length == 0 || arr[0] == null || arr[0]
				.trim().length() == 0);
	}

	/**
	 * Generates a list of Highlighted query fragments for each item in a list
	 * of documents, or returns null if highlighting is disabled.
	 * 
	 * @param docs
	 *            query results
	 * @param query
	 *            the query
	 * @param req
	 *            the current request
	 * @param defaultFields
	 *            default list of fields to summarize
	 * 
	 * @return NamedList containing a NamedList for each document, which in
	 *         turns contains sets (field, summary) pairs.
	 */
	@SuppressWarnings("unchecked")
	public abstract NamedList<Object> doHighlighting(DocList docs, Query query,
			SolrQueryRequest req, String[] defaultFields) throws IOException;
}
